Telephone-exchange system.



*No 862,713I PATENTED AQ. 6, 1907.

M. S. GONNER. TELEPHONE EXGHANGEZSYSTBM.

APPLIUATION FILED MAY 28, 1904.

THE NaRms Fermes sa, wAsmNamN, nA c.

No. 862,713. PATENTED AUG. 6, 1907.

' M. s. GONNER.

` TELEPHONE` EXCHANGE SYSTEM.

APPLIOATION FILED mma. 1904.

2 SHEETS-SHEET 2.

1H: Nnfmls Firmas co., WASHINGTON, D. c.

UNITED STATES PATENT EEICE.`

MERRITT S. CONNER, OF ROCHESTER, NEW YORK, ASSIGNOR TO STROMBERG-CARLSONTELEPHONE MANUFACTURING COMPANY, OF ROCHESTER, NEW YORK, A CORPO- RATIONOF NEW YORK.

Specification of Letters Patent.

Patented Aug. 6, 1907.

Application filed May 28, 1904. Serial No. 210,224.

To all whom it may concern:

Be it known that I, MERRITT S. CONNER, a citizen of the United States,residing at Rochester, in the county oi Monroe and State o New York,have invented a certain -new and useful Improvement inTelephone-Exchange Systems, o' which the following is a full, clear,concise, and exact description, reference being had to the accompanyingdrawings, forming a part of this specification.

My invention relates to telephone exchange systems, and in an exchangeconstructed in accordance with the preferred embodiment oi my inventiona single source of current located at the central oiice is employed tofurnish talking and signaling current for all of the lines associatedwith the central oiiice.

My invention provides a telephone system of great simplicity, but at thesame time a system which is well adapted for use in conjunction withspecial and auxiliary devices, such as pay stations and party lines.

One of theV important features of my invention is that lor bimetallictelephone lines a two-wire multiple system may be employed, eachspringjack having but two contacts, each adapted for connection with alimb of the telephone line, and one of the contacts serving also as atest contact for indicating to the operator whether or not a called lineis busy. It is usually necessary in a two-wire system oi this characterthat the line signal controlling apparatus be actuated by Currentsflowing over one or both oi the conductors which are used also totransmit telephonie voice currents.

My invention provides a telephone system in which the test contact ofthe springjack is normally disconnected from all other parts of thecircuit and in which the other contacts oi the associated springjacksare normally but indirect-ly connected with their telephone line.

My invention introduces a further improvement in the telephone art inthat a differential cut-oft' relay is utilized in such a way that itserves admirably as an impedance coil to prevent the short-circuiting oftelephonie voice currents and to balance inductively the telephone line.

My invention will be clearly understood by reference to the accompanyingdrawing, in which- Figure 1 illustrates diagrammatically a telephoneexchange system constructed in accordance with my invention, and in'which Eig. 2 illustrates substantially the same line circuit as thatshown in Fig. 1, adapted for use in conjunction with a slightly modiliedcord circuit.

Referring to Fig. 1 I have illustrated at each of the substations A andB a subscriber-s common battery telephone set, comprising in eachinstance a `hook switch 3, which, when in its normal depressed position,due to the weight of the receiver 4, serves to connect the signal bell 5with its condenser 6 in bridge of the telephone line limbs 7 and 8, andwhich when relieved of the weight of the receiver serves to connect thetransmitter 9 and the primary 10 of an induction coil in bridge of theline limbs, the secondary 11 of the induction coil being connected withthe receiver 4. The telephone line limbs 7 and 8 lead to the centralstation C, where they are Connected respectively with the armatures 12and 13 of a differential cut-oft' relay 14. The armature 13 normallymakes connection with its back contact 15, whereby the line relay 16 isserially included between the positive pole of the common battery 17 andthe line limb 8. The line relay 16 controls the local circuit for a linelamp 18 or other .signaling device by means of the relay armature 19.The armature 12 normally makes connection with its back contact 20, towhich is connected one terminal of the winding 21 of the differentialrelay 14. The other terminal of this winding is connected with the 'rontcontact 22 of the armature 12, with the tip contacts 23, 23 of themultiple springjacks 24, 24, and also with the other winding 25 oi thecut-oftrelay. These two windings, as shown, are preferably serially anddifferentially connected. Each winding may be wound to approximately 200ohms resistance. The sleeve contact 26, 26 ot the multiple springjacks,which serve also as the test thimbles, are connected directly with theiront Contact 27 ot' the cut-off relay armature 13. The operators cordcircuit provides means for inter-connecting two lines for conversation.The answering plug 28 comprises the tip contact 29 and the sleevecontact 30, these contacts being connected with the tip contact 31 andthe sleeve Contact 32 oi the calling plug' 33 by means of the sections34, 35 oi the tip strand and the sections 36 and 37 of the sleevestrand, these sections being conductively 4insulated by means of theserially connected condenscrs 38 and 39, the condensers serving in thewell known manner to transmit the telephonie Voice currents from oneline to another. The listening key 40 serves to connect the operator-stelephone set 41 in bridge of the cord strands, the induction coil ofthis set being provided with a tertiary winding 42 connected between thecontact 43 and the ground G, the negative pole ot the common battery 17being connected also with the ground. The ringing key 44 serves toconnect the source ot alternating or pulsating ringing current 45 withthe called line. The supervisory controlling relay 46 is connectedbetween the section 34 of the tip strand and the positive pole of thebattery, while the supervisory relay 47 is connected between section 36of the sleeve strand and the same pole oi the battery. The relay 46 ispreferably of 1000 ohms resistance, while the resistance of thesupervisory relayy 47 may be of but 200 ohms resistance. The armature48, with its front contact 49, and the armature 50, with its backcontact 5]., jointly control the associated supervisory signal lamp 52.The calling side of the cord circuit is provided in the same manner withthe supervisory controlling relay 53 connected between section 35 of thetip strand and the positive pole of the battery, the supervisory relay54 being connected between the positive pole of the battery and thesection 37 of the sleeve strand of the cord circuit. These relays areprovided respectively with the armature 55 and its front contact 56 andwith the armature 57 and its back contact 5S, these armatures andcontacts jointly controlling the local circuit for the supervisorysignal lamp 59. The supervisory controlling relay 53 may be of 1000 ohmsresistance, while the relay 54 is of 200 ohms resistance.

The operation of this embodiment of the system of my invention may bedescribed as follows: The subscriber at substation A, in initiatingl acall, removes his receiver from the switch hook, thereby closing acircuit which may be traced as follows: from the positive pole of thecommon battery 17, through the line relay 16, contact l5, armature 13 ofthe cut-off relay, line limb 8, thence through the transmitter andprimary induction coil winding at substation A, and thence by means ofthe switch hook 3 to line limb 7, this limb of the line leading to thearmature l2 of the cut-off relay, and thence normally through the backContact 20, the serially connected windings 2l and 25 of thedifferential cut-off relay 14 to the grounded negative pole of thecommon battery. Current flowing through this circuit will not cause anet energization of the cut-off relay on account of the differentialrelation of its coils, each tending to neutralize the effect of theother. The line relay will be energized, however', thereupon causing theattraction of its armature and the closure of a local circuit throughthe line signal 18. The illumination of this lamp indicates to thecentral office operator that a connection is desired and the signal isthereupon answered by the insertion of the answering plug 28 into theanswering springjack 24 associated with the line to substation A. Uponthe insertion of this plug the following circuit is closed: from thepositive pole of the battery through the supervisory controlling relay46, and thence to the tip contact 23 of the springjack which leadsthrough the winding 25 of the differential cut-off relay to the negativepole of the battery. This circuit of decreased resistance through thewinding 25 serves to permit an excess of current to flow therethrough,thereby unbalancing the effect of the relay winding 21 and causing a netenergization which serves to actuate the armatures 12 and 13,withdrawing each from its back Contact and causing connections to bemade with the front contacts, as shownA .lt will be noted that thisenergization of the cut-off relay serves to break the circuit throughthe line relay, whereupon the latter is denergized to permit theretraction of its armature 19 and the consequent extinguishment of theline signal 18. The actuation of the armature 13 serves also to connectthe sleeve contacts of the spring-jacks directly with the line limb 8.The attraction of the armature l2 `from its back Contact 20 serves tointerrupt the current fiowing through the differential-winding 21 of thecut-off relay.

My invention provides a distinct improvement over certain circuits 'ofthe prior art in that one winding of the cut-off relay is notshortcircuited upon the attrac tion of the associated armature, such ashort-circuiting of a winding of a differential cut-off relay causing amaterial reduction in the impedance of the other winding, which mightotherwise be used to choke the flow of voice current and to balanceinductively the line circuit.

The connection which is established between the armature 12 and thefront contact 22 serves to connect the tip contacts 23 of the multiplespringjacks directly with the line limb 7. Upon the insertion of theanswering plugI into a jack of a calling line the circuit is closed fromthe positive pole of the battery through the supervisory relay 47, thesection 36 of the sleeve strand, contacts 30 and 26, front contact 27,armature 13, line limb 8, the substation transmitter and primary windingof the induction coil, the switch hook 3, line limb 7, armature l2,Contact 22, winding 25 of the cut-off relay and thus back to thenegative pole of the battery. Current flowing through this circuitcauses an energization of the supervisory relay 47, whereupon itsarmature 5() is attracted, thereby breaking the otherwise closed circuitthrough the associated supervisory signal lamp 52. The operator, afterinserting the answering plug, manipulates her listening key to connecther telephone set with that of the calling subscriber, whereupon sheascertains the number of the line with which connection is desired.Learningthat the line leading to substation B is called for, she firstapplies the testing tip Contact 3l of the calling plug to the testthimble of a multiple jack associated with the line to substation A. lfthis line is not in use, the differential cut-off relay armatures willbe in their normal position, as shown, and the test contacts of thespringjacks will be disconnected from all other parts of the apparatus.No current will therefore be caused to flow through the tertiary winding42 of the operators telephone set and no click will be produced in theoperators ear. lf, however, the line to substation B is busy, a plugwill have been inserted in one of the multiple springjacks associatedwith this line and the associated cut-off relay will have been actuated.When, therefore, the operator applies the testing tip contact 31 of hercalling plug to a multiple springjack of the line, a circuit will beclosed as follows: from the grounded negative pole of the common batterythrough the tertiary winding 42 of the operators induction coil, to thecontact 43 of the listening key through section 35 of the tip strand tothe contact 3l, test thimble 26 of the called line, the sleeve contactof the other cord plug, and a relay of the other cord circuitcorresponding with the supervisory relay 47 or with the relay 54, shownin Fig. l, and thence to the positive pole of the battery 17. Currentflowing through this circuit will cause a click in the operatorstelephone, indicating to her that the called line is busy. Assuming thatthis line has been tested and found idle, the operator inserts hercalling plug, thereupon closing the following `circuit; from thepositive pole of the battery, through the supervisory' controlling relay53, section 35 of the tip strand of the cord circuit, tip contact 31,tip spring scar/'13 23 of the multiple jack into which the plug isinserted, winding 25 of the differential cut-off relay and thence to thenegative pole of the battery. Current flowing through this circuitcauses an energization of the cutoff relay, whereupon its armatures areattracted, at once opening the circuit which might otherwise be closedthrough the line relay 16 upon the removal of the called subscriber-1stelephone from its switch hook and serving also to connect the mainterminals or contacts 0lthe springjacks directly with the line limbsleading to substation B. The operator then manipulates her ringing key44 to connect the source of signaling current 45 across the line limbs,whereupon the signal bell at the substation B is actuated to call thesubscriber to his telephone. Upon answering the call the subscriberremoves his receiver from the switch hook,

thereupon closing a conductive path for current and permitting anenergization of the supervisory relay 54, whereupon its armature 57 isattracted, breaking connection with the back contact 5S and thereuponcausing the extinguishment of the supervisory lamp 59 which will havebeen illuminated upon the energization of the supervisory controllingrelay 53 when the plug is inserted. The extinguishment of this lampindicates to the operator that the call has been answered by thesubscriber' at substation B. Either subscriber, upon finishing theconversation, replaces his telephone receivcr upon the switch hook,thereby interrupting the path for current through the associatedsupervisory relay 47 or 54, as the case may be, whereupon the retractionof the respective armature causes the illumination of the associatedsupervisory lamp to indicate to the operator that the conversation hasbeen completed and that the cord-connecting plugs should be removed fromthe springjacks. Upon removal of these plugs the apparatus is restoredto its normal condition.

1n Fig. 2 1 have illustrated substantially the same line circuit andhave applied to each of the various parts the same reference characteras that shown in Fig. 1, except for the addition of the index 1. 1n thearrangement shown in Fig. 2 the windings of the cutoff relay arepreferably of 1,000 ohms resistance each, while the supervisory relaysand supervisory controlling relays are then wound to a resistance of20() ohms each.

A brief explanation of the operation of the circuit shown in Fig. 2 willsuffice to make clear this embodiment of my invention. A subscriber atsubstation A1, upon removing his telephone from the switch hook, causesan actuation of the line relay, whereupon the line lamp is illuminated,thereby attracting the attention of the operator, who inserts heranswering plug, whereupon the following circuit is closed: from thepositive pole of the common battery 171, through the winding of thesupervisory controlling relay 461, to the tip contact 291 of theanswering plug, thence through the tip spring 231 of the springj ack andthrough the winding 251 of the differential c ut-.off relay, to thenegative pole of the battery. The additional current caused to ilowthrough this winding 251 upon the insertion of the answering plug,causes a net energization of the cut-off relay, whereupon its armaturesare attracted to open the circuit through the line relay and to connectthe main terminals of the springjacks directly with the line limbs. Theinsertion of the answering plug into a calling line causes the closureof an additional circuit, which may be traced from the negative pole ofthe battery through the supervisory relay 471 to the section 361 of thesleeve strand of the cord circuit, thence through sleeve contacts 301and 261 to contact 271, the armature 131, line limb 81, the subscriberstelephone apparatus, line limb 71, armature 121, contact 221, tip spring231, tip Contact 291, tip strand 341, and through the winding ofsupervisory controlling relay 461 to the positive pole of the battery.The energization ofthe supervisory relay 471, due to current flowingthrough this circuit, causes theattraction of its armature 501 tointerrupt the otherwise completed eir- Cuit through the supervisory lampsignal 521. With this explanation of the operation of the supervisorysignaling apparatus, the mode of operation of the other parts of thesystem will be made clear.

1n the modification shown in Fig. 2 the tertiary winding of theoperators induction coil should be connected with the positive pole ofthe battery in order to provide the busy test, as will be readilyunderstood by those skilled in the art. 1n this modification the currentis fed to the subscribers telephone instruments principally through thesupervisory signaling relays. These relays are therefore made ofcomparatively low resistance.

1n the modication shown in Fig. 1 the current is fed to the substationapparatus partly through the supervisory relay of 200 ohms resistanceand partly through the 200 .ohm winding of the cut-off relay, and inthis modification of Fig. 1 it is desirable, therefore, that there be noshort-circuited winding upon the cutoff relay, as, for instance, thewinding 21, which could cut down the impedance of the coil 25.

While 1 have herein shown and described a preferred embodiment of myinvention, together with a single application relating to the cordcircuit to be employed in association therewith, it will be understoodby those skilled in the art that many other modifications may beemployed without departing from the spirit of my invention. 1 do notwish, therefore, to limit myself to the precise constructions herein setforth, but

Having described my invention I claim as new and desire to secure byLetters Patentz- 1. In a telephone exchange system, the combination witha telephone line extending by its limbs from a substation to anexchange, of cord-connecting apparatus at the exchange for connectingsaid line with another for c.n\'fersaton, a cutott relay having twodifferential wind ings normally serially included in a single line, aline signal controlled by switching apparatus at the substation, andmeans whereby the connection of the cord-connecting apparatus with saidline causes an actuation of said relay to destroy the substation controlof said line signal and to open the circuit through one of the windingsof said cut-oft' relay.

In a telephone exchange system, the combination with a telephone lineextending by its limbs from a substation to an exchange, ofcord-connecting apparatus at the exchange for connecting said line withanother for conversation, a cut-oir relay having two differentialwindings serially included in a single limb of said line, a line signalcontrolled by switchingT apparatus at the substation. and means wherebythe connection of the cord-connecting apparatus with said line causes anactuation ot said relay to destroy the substation control of said linesignal and to break the circuit through one of the windings of saidcut-ott relay.

3. In a telephone exchange system, the combination with a telephone lineextending by its limbs from a substation to an exchange, of a source ofcurrent at the exchange for supplying current to the substationtransmitters, cord-connecting apparatus for connecting said line withanother for conversation, a cut-off relay having two differentialwindings normally serially,included in an electrical path between oneterminal ot' the source ot' current and substation apparatus, a linesignal normally serially included in circuit with the telephone line,and means whereby the connection of said cordconnecting apparatus withsaid line causesan actuation of said relay to disconnect said linesignal from the telephone line and to open the circuit through one ofthe windings of said cut-oft' relay.

4. Inv a telephone exchange system, the combination with a telephoneline extending by its limbs from a substation to an exchange, of'cord-connecting apparatus at the exchange for connecting said line withanother for conversation, a cut-ott relay having two differentialwindings normally serially included in a single limb of said line, aline signal controlled by switching apparatus at the substation, andmeans whereby the connection of said cord-connecting apparatus with saidline causes the clo sure of a circuit through a winding ot' said relay,thereby causing an actuation of said relay to disconnect said linesignal from the telephone line and to break the circuit through one ofthe windings of said dilerential cut-oft relay.

5. In a telephone exchange system, the combination with a telephone lineextending by its limbs from a substation to an exchange, ot'cord-connecting apparatus at the exchange for connecting said line withanother for conversation, a cut-oft relay having two differentialwindings serially included in a single limb of said line, a line signalcontrolled by switching apparatus at the substation, and means wherebythe connection of said cord-connecting apparatus with said line causesthe closure of a circuit of decreased resistance through a winding ofsaid relay, thereby causing an actuation thereof to destroy thesubstation control of said line signal and to interrupt the circuitthrough on'e of the windings of said cut-off relay.

G. In a telephone exchange system, the combination with a telephone lineextending by its limbs from a substation to an exchange, of a course ofcurrent at the exchange for supplying current to the substationtransmitters, a cut-oil relay having two differential windings normallyserially included in one of said limbs between one terminal of saidsource of current and the substation apparatus, a line signal normallyserially included in the other of said limbs between the other terminalof said source of current and the substation apparatus, a springjack atthe exchange having a tip contact permanently connected to the commonterminal of said differential relay windings, and a sleeve contactnormally disconnected from said line, cord-connecting apparatusassociated with said source of current for connecting said line withanother for conversation, means whereby the insertion of a plug of saidcord connecting apparatus within said jacli' closes a circuit ofdecreased resistance through one winding of said differential cut-offrelay to cause an actuation thereof, switching means controlled by theactuation of said cut-oft' relay to open the circuit from a terminal ofsaid source of current through said line signal to one limb of the lineand to connect said limb to the sleeve contact of the springjack, andother switching means controlled by the actuation of said cut-olt` relayto open the circuit oi' the winding of said cut-oft relay connected between the tip contact o1 the springjack and one limb of the line.

7. In a telephone exchange system, the combination with a telephone lineextending by its limbs from a substation to an exchange, of cordconnecting apparatus at the exchange for connectingsaid line withanother for conversation, a cut-oli relay having two differentialwindings serially included in the circuit with said line, a spring jackcontact at the central exchange normally disconnected from the line atone armature of said relay, another spring jack contact normallyconnected with a line through part of the relay winding and throughanother armature thereof, and means upon connection ot said connectingapparatus with the spring jack for causing actuation of said relaywhereby the iirst mentioned contact is connected with the line and thesecond mentioned contact directly connected with the line.

8. In, a telephone exchange system, the combination with a telephoneline extending by its limbs from a substation to an exchange, of cordconnecting apparatus at the exchange for connecting said line withanother for conversation, a cut-oit relay having two differentialwindings normally included serially in the line circuit, switchingmechanism controlled by said relay, a spring jack con` tact at thecentral exchange normally disconnected from one line limb by saidswitching mechanism, a second spring jacl: contact normally connectedwith the other line limb through said switching mechanism and throughpart of the relay winding, and means upon connection of said cordconnecting apparatus with the spring jack contacts for causing actuationof' said relay and switching mechanism whereby the first spring jackcontact is connected with the one line limb and the second spring jackcontact di rectly connected with the other line limb.

9. In a telephone exchange system, the combination with a centralexchange, of a telephone line extending therefrom, cord connectingapparatus at t'he exchange, a cut-off relay having two dlerentialwindings normally serially included in the line circuit, switchingmechanism controlled by said relay, a spring jack contact normallydisconnected from one line limb at said switching mechanism, a secondspring jack contact normally connected with the other line limb throughsaid switching mechanism and through one of said relay windings, andmeans upon connection of said cord connecting apparatus with said springjack contacts for causing energization of said relay and actuation ofsaid switching mechanism whereby said first spring jack contact isconnected with the one line limb and the second spring jack contactdirectly connected with the other line limb and whereby one of saidrelay windings is entirely disconnected from circuit.

10. In a telephone exchange system, the combination with a centralexchange, of a telephone line extending therefrom, cord-connectingapparatus at the central exchange for connecting said line with another,a cut-oit relay having two differential windings normally seriallyconnected in one of the line limbs, switching mechanism for said relay,a line signal normally serially included in the other line limb at saidswitching mechanism, a springjack contact normally disconnected from oneline limb through part ot' said switch mechanism, a second springjackcontact normally connected with the first line limb through another partof said switching mechanism and through one of said differentialwindings, and means upon connection of said cord connecting apparatuswith the spring jack contacts for causing an additional circuit throughone of the differential windings whereby said relay becomes energizedand its switching mechanism actuated, actuation of' said switchingmechanism causing dis"- connection of the line signal from the otherline limb, connection therewith of the first spring jack contact andconnection of the second spring jack contact directly with the tirstline limb and exclusion from circuit of the winding through which saidsecond spring jack is normally connected with the rst line limb.

11, ln a telephone exchange system, the combination with a telephoneline extending from a central exchange to a substation, ot' cordconnecting apparatus at the central exchange for connecting said linewith another, a cutoll' relay having a winding normally entirelyincluded in one limb ofthe line circuit, said winding being normallybalanced to prevent energization ot the relay, a spring jack contactnormally entirely disconnected from one line limb, a second spring jackcontact normally connected with the other line limb through part ot' therelay winding, and means upon connection of said cord connectingapparatus with said spring jack contacts for causing unbalance of therelay winding, whereby said relay is energized and whereby said springjack contacts are directly connected with the line limbs.

12. in a telephone exchange system, the combination with a telephoneline extending from a substation to an exchange, of a source of`currentat the exchange, cord connecting apparatus at the exchange, a cut offrelay having two differential windings serially included in a singleline lin1b of said line, a line signal controlled by switching apparatusat the substation, and means whereby the connection of the cordconnecting' apparatuswith the line causes an actuation of said relay todestroy the substation control of said line signal and to open thecircuit through one of said differential windings.

13. ln a telephone exchange system, the combination with a telephoneline extending from a substation to an exchange, of cord connectingapparatus at the exchange, a cut ott' relay at the exchange having allits windings normally serially included in one line limb, a line signalcircuit controlled by the cut off relay, and means adapted uponconnection of the cord connecting apparatus with a l5 line for causingpart of the relay winding to be disconnected from circuit and the linesignal circuit opened.

ln witness whereof, I hereunto subscribe my name this 18th day of May A.D., 1904.

MERRITT S. CONNER.

Witnesses H. E. BALL, A. J. MAHAN.

